Chemical feeder



CHEMICAL FEEDER Joseph J. Tepas, Jr. and Gerard C. Smith, Baltimore,Md., assignors to Olin Mathieson Chemical Corporation, a

corporation of Virginia Application May 2, 1951, Serial No. 224,240

1 Claim. (Cl. 2111-28) a flowing body of the liquid to be treated. Suchpractice requires the purchase of solutions of hypochlorite or requiresthe preparation of a stock solution from a dry hypochlorite at the pointof use. Sodium hypochlorite known in the solid state onlyas thepentahydrate, avery unstable compound, is prepared commercially assolutions not exceeding 15% available chlorine, which solutionsdeteriorate quickly'during shipment and storage and are. generallyavailable only in the vicinity of plants in which they are prepared.Calcium hypochlorite, on the other hand, particularly in the form ofhigh test hypochlorite, can be shipped as a relatively stable solidcontaining 70% or more of available chlorine and may be convenientlystored for long periods of time without appreciableloss of availablechlorine.

In spite of the above .and otheradvantages of solid calcium hypochloritefor use as a sterilizing agent, there is the problem of applying thesolid in such a manner that only' afewpartsper million of availablechlorine will ultimately be presentin the water or other liquid to betreated, which remains the chief reason for the continued use of sodiumhypochlorite solutions. In the conventional method of application, forexample to the circulating system of a swimming pool, the solid calciumhypochlorite is dissolved in water to form a supply or stock solution ofdesired concentration which is metered by a sensitive metering deviceinto the circulating system at a rate that will maintain residualchlorine of 0.3 to 0.6 p. p. m. in the pool. However in the conventionalmethod of application thereis the difiiculty of sludge formation-'in-making -up-the"stock solutions. The presence of sludge in thehypochlorite solutions tends to clog the sensitive metering devicesnecessary to supply the calcium hypochlorite solution in small amountsto the body of liquid to be treated. Consequently it is often necessaryto filter or otherwise separate the sludge from the calcium hypochloritesolution prior to passing the solution through the metering device.

With the apparatus of our invention a material in solid particulateform, such as calcium hypochlorite, may be effectively and continuouslydissolved at variable but accurately controllable rates and theresulting solutions, covering a wide range of available chlorinedispensations, may be supplied without further treatment to the point ofultimate consumption.

In general the apparatus of the present invention comprises a verticallyenlarged container with an upper opening for charging the solidhypochlorite and a lower opening for withdrawing aqueous hypochlorite, aperforated support for a bed of the solid hypochlorite arranged withinsaid container and above its base, distributing means set above saidperforated support and containing a plurality of parallel openings forintroducing 'fine parallel streams of water horizontally into saidcontainer and distributing it throughout the lower portion of thehypochlorite bed, means for metering variable amounts of water to saiddistributing means, and means for withdrawing and dispensing aqueoushypochlorite solution of desired concentration from said lower opening.

In operation water is metered at an accurately controllable but variablerate to the distributing device set in the sideof the container anddistributed into the lower fraction of the bed of calcium hypochloritecharge. The charge is dissolved by the water andthe solution so formedpasses through the perforated :support for the charge, through the exitin the container, through the dispensing means, and into the flowing orcirculating body of liquid to be treated. The bed of calciumhypochlorite charge in the lower portion of the container is replaced asdissolved by the charge descending by its own weight from the uppersection of the container. Thus the apparatus of the present inventionprovides means for dissolving calcium'hypochlorite 'in tableted form atvariable but accurately controllable rates at which available chlorineis required for treatment of water and dispenses with the necessity ofpreparing large quantities of stock solutions of calcium hypochlorite.Furthermore, the apparatus of the present invention has the importantadvantage of permitting control of the flow rate of the calciumhypochlorite solution into the body of liquid to be treated by meteringthe water instead of by metering the calcium hypochlorite solution. Theproblem of sludge removal to prevent clogging of the metering equipmentis thereby eliminated since the sludge flows freely into the body ofliquid to be treated where it is dissolved. 1

In any system where water is supplied under pressure, or is beingcirculated by a pump, the installation of the present apparatus requiresonly a connection for the inflow water to the high pressure side of thesystem and a connection for introducing the resulting solution at a lowpressure point in the system.

A useful feeder exemplifying our invention is illustrated somewhatdiagrammatically in the accompanying drawings in which:

Fig.-. 1 is a vertical cross-section of a feeder employing theprinciples of our invention.

Fig. 2 is a view taken at line 22 of Fig. 1 showing the device utilizedfor introducing and distributing the water into the bed of calciumhypochlorite. The arrangement shown in the accompanying drawings wasdesigned to best suit the needs of a specific application and is in noway meant to express or imply a limitation or restriction on thedesign.-

As Fig. 1 shows, the apparatus consists of a top 9, bottom 10, andcenter section 11, which are held together by tie-rods 12 and nuts 13. Alid 14 held firmly in place by wing nut 15 and conveniently providedwith a vent =16 affords a convenient means of charging the chemicalthrough the top 9.

- In operation, water is advantageously filtered througha suitablestrainer 17 and supplied to the feeder through line 18, at arate whichis measured by a flowmeter 19, and controlled by a suitable needle valve20. This water is passed through line 21 to the distributor tube 22 andis injected into the lower part of the feeder through small parallelorifices 23. Thus the water only wets a small portion of the bed ofcalcium hypochlorite contained in the feeder, leaving the rest to serveas a gravity-feed supply. The distributor tube may be placed in anyexpedient manner which permits the water to contact only the lowerportion of the bed of calcium hypochlorite and be suitably distributedtherein. How ever it is advantageously placed in the side of thecontainer and the water introduced horizontally in the form of finestreams from the outside so as to avoid the necessity of internalequipment which would interfere with the descending hypochlorite chargeand cause arching of the charge. The resulting solution passes through aperforated plate 24, provided at a suitable distance from the bottom ofthe feeder. This plate 24 supports the bed of hypochlorite and forms achamber below which may accumulate a backflow of solution withoutpermitting the wetting of the bulk of the hypochlorite stored in thefeeder. From this chamber the solution fed through line "25"Withstopcock 26 to the point of applieationt- The design principles of: thepresent invention can generally be used advantageously when it isdesired to dispensemolutions: ft chemicalassuppliedxin:solidsparticulateiorm z-atr; accuratelyucontrolled natesuwhichvmay. bevaried. simply controlling-lithe. solvent input'mate; It is particularlyuseful in the application of solid calcium hypoclrlorite tol'zbodiess ofmoving liquids :such; :as, for examplerrimtreaning water of swimmingepoolsnwater plantsnin smallzmunicipalities;itbottling plants; dairies;cooling systems; :etc., :where; the addition of. alzsterilizingagentzsis desirahlenczilt also can be; advantageously used in thetreatment-bi: industrialzzwastes 12m destroy lCOlOF,OdOIZ,;l,'IIldJOXiClZCOl'lSfitUGfltS;and :ior odom antibacterialcontrol: he sewage: elfluents; :1 'BI'ESSCdLIfiblEISL of... calciumhypochlorite: are especially suitable: in; the presentsappaeratus,:;;bnt othenzshapes: and 'sizesuof particlesvmayialso be usedlfhe: apparatus iS.1 adaptableion dissolving'and feedingafiother:chemicals-,;: for example usodium; fluoride inminor amountsrfon: watersupplies,polyphosphates. and compositions: containinglithern tor watersofteniiiggnsoda ash iurnishediaszbriquettesaorefusedsodmash fonadjusts: ing the: alkalinity of-razl-treating :solution, :etc.. e;Theimaterialsnf construction imcontactuwitlnthe solid or solutions of:calcium -hypoohloritel:are preferably TGSiSIEHELTO? its action;Particularly :suitable .tor: this purpose =.-are aconsiderablezlnumben.ofwplastic; compounds 7 of this apparatus using Theunit described in Example I was installed across the recirculating pumpofuaoswirnming pool. By means high test hypochlorite tablets thechlorine residual-' of the 65;000 g"al. pool could be suclr, as; forexample; Lucite: which :has Ithe additional advantage ofistransparencylOthemportions; of; the. 1 appaa ratus mayz'rbe construotednfmoldediresins and @EECOH ventionalnmaterialsr*includingu coppenz brass,steely :etc.

The apparatus: ofwthe. presentuinventionzcan be? fabrie cated'eatslowcostucompareda to:.other dispensing,.;.equip.a

ment. It is of compact construction, cant'be; quickly installed;reiquireso'zazaminimunrofi maintenance ds safe to use and ,=involves..no accident. hazardsa: It" requires the preparation ofi no stocksolutions acts the chemicals usedu-x: Oncecharged .tset iti'ican. to.operate; reliably: .svithoutt:furtheriattention. until the charge ofsolid chemica-Lis; spentu :With azsuitable-meter i-ng'deyicexcontrolling; the, inflowzof water, the degree of" treatment; leanbe varied :ouer: widexrlimits: :andscan be be depended upon changedquickly to accommodate fluctuations in demand.

The .follofwingzexamples-zillustratezspecifie;instancesaof operation ofthe apparatussofirourinvention :21

Example. I"

cated that by means of this partictflanapparatusshypor chlorite;solutions; couldsbe:.dispensedsaeeuratelm and relibrought. tromsfi to0.50..p. p. ,m. in 12 minutes.v The operator of the pools:a1";nonetechnicakmamf quickly learned to use this feeding device to bestfa'dvantage. Thus, after bringing the chlorine'resid'ualofhis'pool up toO.5Q.tp.-.,-p. :m., experienceaquieklyataughtlhim .how to set hisflowmeter so that for any particular t'ypeot load a fairlyconstants:residuala'conld:be; maintained without further adjustment.

Example III v ,Anothenunit. comprising-the samefdesigwand dir'nen: sionsdescribed in Example. I was "installed across-the recirculating pumpOff?! $200,000 gal. poolp" This 'opera;- tor preferred a lowQ-initialxrate oi: dispensation which duringwthe preliminary periqd zbuilt up"theavailable chlorine .content sufiiciefit to accommodate the peakloadand maintain arr.adequate'residualat all times but'witlu out changingthe flowmeter"setting' "to maintain this residual throughout theduration 'ofithe: swimming'period;

We claim:-

Apparatus for preparingmndtfeeding aqueousrhypm chlorite solutions ofcontrolled-concentration'fronr'solid hypdchlorite whichc.omprisesa'verticallyenl'arged container with an upper i opening: for charging.solid' hypochlorite. and a lower, opening for withdrawingaqueoushypochl'orite', a perforatedsupport for a'bed ofthe solid" hypochlorite;arranged'rwithinthe said-cdntainer 'and above its base and said loweropening; distributing" means set in the side-cf; said'ficontaineifabovesaidrperforated support, said distributingmeans-containing a pluralityof parallel openings .for introducing'fine parallel-streams of water,horizontally'into'isaid'containerfrom 'its side and distributing thewater *throughoutthe l'ower'portion of the hypochlorite bed,'meansfornietering-arariable amounts ofswa'ter to'saidi'd'istributih'gjmeans;and means for withdrawing xand 'dispensingnqueous'. hypochlorite solution of desired "concentration from saidlower 'openmg.

References Gited :imthe file ofitthis patentm UNITED STATES "P'ATENTS

